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US4638735A - Combustion inhibitor based on an aliphatic polyurethane elastomer for a propellant, and block coated with this inhibitor - Google Patents

Combustion inhibitor based on an aliphatic polyurethane elastomer for a propellant, and block coated with this inhibitor Download PDF

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Publication number
US4638735A
US4638735A US06/735,368 US73536885A US4638735A US 4638735 A US4638735 A US 4638735A US 73536885 A US73536885 A US 73536885A US 4638735 A US4638735 A US 4638735A
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Prior art keywords
molecular weight
inhibitor composition
polymer
inhibitor
combustion
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US06/735,368
Inventor
Andre E. Lelu
Jean R. Grignon
Bruno F. Gonthier
Jean-Michel Tauzia
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Societe Nationale des Poudres et Explosifs
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Societe Nationale des Poudres et Explosifs
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Assigned to SOCIETE NATIONALE DES POUDRES ET EXPLOSIFS reassignment SOCIETE NATIONALE DES POUDRES ET EXPLOSIFS ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: GONTHIER, BRUNO F., GRIGNON, JEAN R., LELU, ANDRE E., TAUZIA, JEAN-MICHEL
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Classifications

    • C—CHEMISTRY; METALLURGY
    • C06—EXPLOSIVES; MATCHES
    • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
    • C06B23/00—Compositions characterised by non-explosive or non-thermic constituents
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/40—High-molecular-weight compounds
    • C08G18/4009—Two or more macromolecular compounds not provided for in one single group of groups C08G18/42 - C08G18/64
    • C08G18/4018—Mixtures of compounds of group C08G18/42 with compounds of group C08G18/48
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/40—High-molecular-weight compounds
    • C08G18/48—Polyethers
    • C08G18/4804—Two or more polyethers of different physical or chemical nature

Definitions

  • the present invention relates to a combustion inhibitor composition for a propellant, based on an aliphatic polyurethane elastomer.
  • combustion inhibitor composition having high discreteness and based on an aliphatic polyurethane elastomer obtained by the reaction of at least one polyisocyanate with a mixture of oxygenated polymers.
  • Combustion inhibitors are materials employed to cover the surfaces of a block of propellant, except for the combustion surface. Thus, these materials protect the surfaces of the block against any unintended ignition which could occur, especially under the effect of the hot gases produced by the combustion of the block.
  • the combustion inhibitors therefore make it possible to control the combustion of a block of propellent by making it possible to determine and preserve a zone of uniform combustion while the latter runs its course.
  • Disreteness is characterised by the degree of transparency of the gases emitted to the guidance waves, particularly infrared and visible radiations.
  • propellants which are discrete by their nature are propellants known as "double-base", the combustion gases of which contain very few or no solid particles, and are consequently transparent to the radiations.
  • a combustion inhibitor must therefore have, in particular, the following properties:
  • a first solution has been offered to meet these requirements, which consists in using a material which is ablated during the combustion of the propellant, producing transparent gases. This material is thus “gasifiable” under the effect of the hot gases produced by the combustion of the propellant.
  • the second solution offered consists in the use of materials which have excellent thermal behaviour, such as materials with a silicone binder, which remain in the combustion chamber and therefore do not release obscuring particles.
  • the inhibitor compositions of the present invention correspond to the materials of the first solution, and are therefore materials referred to as gasifiable.
  • the subject of the present invention is combustion inhibitor compositions of the type of the known compositions based on an aliphatic oxygenated polyurethane, but having improved characteristics of transparency to radiations and of control of propellant combustion.
  • the invention offers a combustion inhibitor composition for a solid propelling composition known as a propellant, based on an aliphatic polyurethane obtained by the reaction of at least one polyisocyanate with a mixture of at least one polyetherpolyol containing at least three hydroxy groups per molecule and at least one polymer containing two hydroxy groups per molecule.
  • the difunctional polymer is chosen from lactone polymers and tetrahydrofuran polymers, the respective molar fractions of the difunctional polymer and of the polyfunctional polyetherpolyol are determined by the following relationship: ##EQU1## in which: Mx, ⁇ x and fx respectively denote the molecular weight, the molar fraction and the hydroxy functionality of the difunctional polymer; and
  • My, ⁇ y, fy respectively denote the molecular weight, the molar fraction and the hydroxy functionality of the polyetherpolyol.
  • the molar fractions ⁇ x, ⁇ y denote the concentration of the polyols in the polyurethane mixture formed by the polyols and the diisocyanate.
  • the hydroxy functionality of the polyether polyol or of the difunctional polymer means the number of hydroxyl groups per molecule of the polymer.
  • composition of the invention may optionally contain a gasifiable organic filler and/or a plasticizer.
  • the polyetherpolyols have a functionality of three and a molecular weight of between approximately 400 and approximately 4500, advantageously of the order of 400 to 1000.
  • the lactone polymers have a molecular weight of between approximately 500 and approximately 3000, advantageously between 1100 and 1700.
  • these have a molecular weight of between approximately 600 and approximately 2000, preferably of the order of 1000.
  • compositions of the present invention are characterised by high discreteness. Furthermore, their melting point is higher than that of the compositions consisting of a polyurethane based solely on polyetherpolyols.
  • a combustion inhibitor according to the present invention only an ablation phenomenon of this inhibitor is produced, whilst with an inhibitor consisting of a polyurethane based solely on polyetherpolyols, in addition to the phenomenon of ablation of the inhibitor, a melting of the latter is observed, which results in flows in the combustion chamber capable of giving rise to irregularities in the combustion of the block, and a reduction in the radiation transparency due to the entrainment of liquid particles in the combustion gases.
  • Aliphatic polyurethanes are intended to mean polyurethanes which contain substantially no aromatic moieties. However, these polyurethanes may contain a small proportion of aromatic moieties, but this proportion should not exceed 10% in order not to modify the discreteness characteristics of the inhibitor.
  • the polyurethanes In order for the compositions of the invention to be gasifiable, the polyurethanes must be oxygenated.
  • the proportion of the number of carbon atoms to the number of oxygen atoms present in the polyurethane is below 6 and advantageously between 4 and 5.5.
  • the polyetherpolyols which are suitable for the invention include polyethylene glycol, polypropylene glycol, polypropylene ethylene glycol, polytetramethylene glycol and the like, and the products of addition of polyoxypropylene glycol to ethylene glycol, diethylene glycol, propylene glycol, glycerol, sorbitol, pentaerythritol, trimethylolpropane, for example; it is also possible to use polyesterpolyols derived from dicarboxylic acids such as adipic, succinic or sebacic acids, and from low molecular weight glycols such as ethylene glycol, propylene glycol, diethylene glycol, 1,4-butanediol, 1,6-hexanediol, or the like.
  • lactone polymers which are suitable for the invention are polymers formed from polyfunctional initiators by successive ring opening of lactone monomers.
  • lactones suitable for the invention correspond to the formula: ##STR1## n being below or equal to 4.
  • lactone polymers mention may be made of poly- ⁇ -caprolactone or poly- ⁇ -butyrolactone.
  • the tetrahydrofuran polymer which is suitable is polytetrahydrofuran.
  • polyisocyanates which are suitable for the invention are aliphatic diisocyanates such as 4,4'-diisocyanatodicyclohexylmethane (MDCI), 1,6-diisocyanate-2,2,3-trimethylhexane, isophorone diisocyanate, hexamethylenediisocyanate or the like.
  • MDCI 4,4'-diisocyanatodicyclohexylmethane
  • 1,6-diisocyanate-2,2,3-trimethylhexane 1,6-diisocyanate-2,2,3-trimethylhexane
  • isophorone diisocyanate hexamethylenediisocyanate or the like.
  • the crosslinking is carried out in the presence of catalysts such as, for example, those based on tin, such as dibutyltin diacetate, or dibutyltin dilaurate.
  • catalysts such as, for example, those based on tin, such as dibutyltin diacetate, or dibutyltin dilaurate.
  • the proportion of the NCO groups to the OH groups is preferably 1 or slightly greater. In the preferred embodiment of the invention this proportion is equal to 1.1.
  • an aliphatic plasticizer such as, for example, triacetin or tri-n-butyl acetylcitrate.
  • plasticiser Up to 50 parts by weight of plasticiser may be added to 100 parts of polyurethane.
  • compositions according to the invention may advantageously contain a gasifiable organic filler, this filler having a melting temperature equal to or higher than that of the polyurethane.
  • oxamide ammonium oxalate
  • polyoxyethylene polyoxypropylene
  • polyoxymethylene polyoxymethylene
  • ammonium oxalate polyacetal ammonium oxalate
  • these fillers should be non-hygroscopic, to avoid the presence of water, which interferes with the crosslinking of the polymer.
  • oxygenated organic fillers having a proportion of the number of carbon atoms to the number of oxygen atoms which is closest to the value 1, in order thus to promote the oxidation reactions relative to the polymerization reactions, and consequently to reduce cinder formation.
  • the quantity of fillers which can be added may reach 300 parts by weight of these fillers per 100 parts of polyurethane, the limit of this quantity being determined by the castability of the composition and by the minimum mechanical properties which a combustion inhibitor must have.
  • this filler is oxamide, which has a very high melting point (approximately 400° C.).
  • chain extenders such as low molecular weight glycols such as, for example, 1,4-butanediol, or diamines such as ethylenediamine.
  • the quantity of this trimethylolpropane which is added is determined by the required mechanical properties of the inhibitor, and may be as much as 20 parts by weight per 100 parts of polyols.
  • compositions according to the invention heat-stable organic or inorganic fibres such as polyphenylene terephthalamide fibres marketed by the company Dupont de Nemours under the trade name "Kevlar", for example.
  • the invention is used in accordance with the procedures usually employed in the field of inhibition of blocks of propellant.
  • a block of double-base propellant is arranged concentrically in a cylindrical mould so as to leave a uniform space between the surface of the block and the inner wall of the mould.
  • the constituents of the polyurethane according to the invention are mixed using a mixer.
  • the cooling filler, the plasticizer or the fibres, when provision is made for these components or for one of these in the final composition, are also mixed with the constituents of the polyurethane using the mixer.
  • the propellant block is inhibited by casting the composition in the space provided in the mould or, according to a preferred procedure, by injection-moulding the composition.
  • compositions were tested by firing cylindrical blocks (height 200 mm, ⁇ :90 mm) of double-base propellant of the composition given above, the blocks being inhibited by a layer of these inhibitor compositions 2.5 mm in thickness.
  • the invention offers combustion inhibitor compositions having good discreteness properties and excellent mechanical and combustion control properties.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Polyurethanes Or Polyureas (AREA)

Abstract

The invention relates to a combustion inhibitor composition intended to cover partly the surface of blocks of double-base propellant. The inhibitor composition of the invention includes an aliphatic polyurethane obtained by the reaction of at least one polyisocyanate with a mixture of at least one polyetherpolyol containing at least three hydroxy groups per molecule and at least one polymer containing two hydroxy groups per molecule. This difunctional polymer is chosen from lactone polymers, such as poly-ε-caprolactone and polytetrahydrofuran. The inhibitor composition may also contain gasifiable fillers and an aliphatic plasticizer. The composition has good discreteness properties, while retaining excellent mechanical properties. The present invention has particular application in the field of solid weapon propulsion.

Description

The present invention relates to a combustion inhibitor composition for a propellant, based on an aliphatic polyurethane elastomer.
It relates more particularly to a combustion inhibitor composition having high discreteness and based on an aliphatic polyurethane elastomer obtained by the reaction of at least one polyisocyanate with a mixture of oxygenated polymers.
Combustion inhibitors are materials employed to cover the surfaces of a block of propellant, except for the combustion surface. Thus, these materials protect the surfaces of the block against any unintended ignition which could occur, especially under the effect of the hot gases produced by the combustion of the block.
The combustion inhibitors therefore make it possible to control the combustion of a block of propellent by making it possible to determine and preserve a zone of uniform combustion while the latter runs its course.
In the case of the weapons referred to as "tactical", which are generally guided from the firing post, it is necessary that the combustion of the propellant block, which enables the weapon to travel, does not produce fumes or gases which would obscure the rear zone of the weapon, thus preventing its guidance by the firing post.
This condition, referred to as "discreteness", is characterised by the degree of transparency of the gases emitted to the guidance waves, particularly infrared and visible radiations.
The propellants which are discrete by their nature are propellants known as "double-base", the combustion gases of which contain very few or no solid particles, and are consequently transparent to the radiations.
This condition of discreteness is also applicable to the materials employed to produce the inhibition of the blocks of "double-base" propellant.
For an inhibitor to be discrete it is necessary that the material employed satisfies several requirements which may appear to be contradictory.
Some of these requirements are, for example:
a longitudinal and transverse transparency to the radiations of the gases produced by the combustion, to allow the weapon to be guided;
an endothermic decomposition of the inhibitor layer in contact with the hot gases in order to "cool" this layer to the maximum so as to improve its thermal resistance;
a uniformity of continuous combustion of the propellant over the entire combustion surface and, particularly, absence of a hypervelocity effect on the side edges of the propellant block;
absence of migration of the nitroglycerine present in the "double-base" propellant.
To satisfy these requirements, a combustion inhibitor must therefore have, in particular, the following properties:
resistance to nitroglycerine migration,
no emission of obscuring fumes during the combustion of the propellant,
the ensuring of good adhesion to the propellant block.
A first solution has been offered to meet these requirements, which consists in using a material which is ablated during the combustion of the propellant, producing transparent gases. This material is thus "gasifiable" under the effect of the hot gases produced by the combustion of the propellant.
The second solution offered consists in the use of materials which have excellent thermal behaviour, such as materials with a silicone binder, which remain in the combustion chamber and therefore do not release obscuring particles.
The inhibitor compositions of the present invention correspond to the materials of the first solution, and are therefore materials referred to as gasifiable.
Such gasifiable materials have already been offered, particularly by French Pat. No. 2,275,425, in which the material consists of an aliphatic polyurethane based on a polyetherpolyol, an aliphatic polyisocyanate and a cooling filler.
However, in view of the affinity of the aliphatic polyurethane for nitroglycerine, it was necessary to insert between the inhibitor and the propellant a barrier layer consisting of a polyurethane based on a triisocyanate, to produce a layer containing an extremely tightly-knit lattice.
In order to dispense with this barrier layer, it has been proposed in French Pat. No. 2,444,689 to increase the degree of crosslinking of the polyurethane material by employing polyols of low molecular weight.
The radiation transparency characteristics of these materials still appear to be insufficient, and edge effects which are still significant remain during the combustion in contact with some compositions.
The subject of the present invention is combustion inhibitor compositions of the type of the known compositions based on an aliphatic oxygenated polyurethane, but having improved characteristics of transparency to radiations and of control of propellant combustion.
To this end, the invention offers a combustion inhibitor composition for a solid propelling composition known as a propellant, based on an aliphatic polyurethane obtained by the reaction of at least one polyisocyanate with a mixture of at least one polyetherpolyol containing at least three hydroxy groups per molecule and at least one polymer containing two hydroxy groups per molecule. According to the invention, the difunctional polymer is chosen from lactone polymers and tetrahydrofuran polymers, the respective molar fractions of the difunctional polymer and of the polyfunctional polyetherpolyol are determined by the following relationship: ##EQU1## in which: Mx, γx and fx respectively denote the molecular weight, the molar fraction and the hydroxy functionality of the difunctional polymer; and
My, γy, fy respectively denote the molecular weight, the molar fraction and the hydroxy functionality of the polyetherpolyol.
The molar fractions γx, γy denote the concentration of the polyols in the polyurethane mixture formed by the polyols and the diisocyanate. The hydroxy functionality of the polyether polyol or of the difunctional polymer means the number of hydroxyl groups per molecule of the polymer.
Furthermore, the composition of the invention may optionally contain a gasifiable organic filler and/or a plasticizer.
Preferably, the polyetherpolyols have a functionality of three and a molecular weight of between approximately 400 and approximately 4500, advantageously of the order of 400 to 1000.
According to another characteristic of the invention, the lactone polymers have a molecular weight of between approximately 500 and approximately 3000, advantageously between 1100 and 1700.
As for the tetrahydrofuran polymers, these have a molecular weight of between approximately 600 and approximately 2000, preferably of the order of 1000.
The compositions of the present invention are characterised by high discreteness. Furthermore, their melting point is higher than that of the compositions consisting of a polyurethane based solely on polyetherpolyols. As a result of this, during the combustion of the propellant, with a combustion inhibitor according to the present invention, only an ablation phenomenon of this inhibitor is produced, whilst with an inhibitor consisting of a polyurethane based solely on polyetherpolyols, in addition to the phenomenon of ablation of the inhibitor, a melting of the latter is observed, which results in flows in the combustion chamber capable of giving rise to irregularities in the combustion of the block, and a reduction in the radiation transparency due to the entrainment of liquid particles in the combustion gases.
Aliphatic polyurethanes are intended to mean polyurethanes which contain substantially no aromatic moieties. However, these polyurethanes may contain a small proportion of aromatic moieties, but this proportion should not exceed 10% in order not to modify the discreteness characteristics of the inhibitor.
In order for the compositions of the invention to be gasifiable, the polyurethanes must be oxygenated. The proportion of the number of carbon atoms to the number of oxygen atoms present in the polyurethane is below 6 and advantageously between 4 and 5.5.
The polyetherpolyols which are suitable for the invention include polyethylene glycol, polypropylene glycol, polypropylene ethylene glycol, polytetramethylene glycol and the like, and the products of addition of polyoxypropylene glycol to ethylene glycol, diethylene glycol, propylene glycol, glycerol, sorbitol, pentaerythritol, trimethylolpropane, for example; it is also possible to use polyesterpolyols derived from dicarboxylic acids such as adipic, succinic or sebacic acids, and from low molecular weight glycols such as ethylene glycol, propylene glycol, diethylene glycol, 1,4-butanediol, 1,6-hexanediol, or the like.
The lactone polymers which are suitable for the invention are polymers formed from polyfunctional initiators by successive ring opening of lactone monomers.
The lactones suitable for the invention correspond to the formula: ##STR1## n being below or equal to 4.
Among these lactone polymers, mention may be made of poly-ε-caprolactone or poly-γ-butyrolactone.
The tetrahydrofuran polymer which is suitable is polytetrahydrofuran.
The polyisocyanates which are suitable for the invention are aliphatic diisocyanates such as 4,4'-diisocyanatodicyclohexylmethane (MDCI), 1,6-diisocyanate-2,2,3-trimethylhexane, isophorone diisocyanate, hexamethylenediisocyanate or the like.
The crosslinking is carried out in the presence of catalysts such as, for example, those based on tin, such as dibutyltin diacetate, or dibutyltin dilaurate.
The proportion of the NCO groups to the OH groups is preferably 1 or slightly greater. In the preferred embodiment of the invention this proportion is equal to 1.1.
It is also advantageous to add to the composition an aliphatic plasticizer such as, for example, triacetin or tri-n-butyl acetylcitrate.
Up to 50 parts by weight of plasticiser may be added to 100 parts of polyurethane.
The compositions according to the invention may advantageously contain a gasifiable organic filler, this filler having a melting temperature equal to or higher than that of the polyurethane.
The following may be mentioned as suitable fillers, by way of indication: oxamide, ammonium oxalate, polyoxyethylene, polyoxypropylene, polyoxymethylene, and ammonium oxalate polyacetal.
Preferably, these fillers should be non-hygroscopic, to avoid the presence of water, which interferes with the crosslinking of the polymer.
It is preferred to use oxygenated organic fillers having a proportion of the number of carbon atoms to the number of oxygen atoms which is closest to the value 1, in order thus to promote the oxidation reactions relative to the polymerization reactions, and consequently to reduce cinder formation.
The quantity of fillers which can be added may reach 300 parts by weight of these fillers per 100 parts of polyurethane, the limit of this quantity being determined by the castability of the composition and by the minimum mechanical properties which a combustion inhibitor must have.
In the preferred embodiment of the invention, this filler is oxamide, which has a very high melting point (approximately 400° C.).
Furthermore, it is possible to add to the composition of the invention chain extenders such as low molecular weight glycols such as, for example, 1,4-butanediol, or diamines such as ethylenediamine.
In addition, it is possible to add a very low molecular weight polyol such as, for example, trimethylolpropane.
The quantity of this trimethylolpropane which is added is determined by the required mechanical properties of the inhibitor, and may be as much as 20 parts by weight per 100 parts of polyols.
It is also possible to add to the compositions according to the invention heat-stable organic or inorganic fibres such as polyphenylene terephthalamide fibres marketed by the company Dupont de Nemours under the trade name "Kevlar", for example.
The invention is used in accordance with the procedures usually employed in the field of inhibition of blocks of propellant.
One of these procedures will be described hereafter by way of illustration: a block of double-base propellant is arranged concentrically in a cylindrical mould so as to leave a uniform space between the surface of the block and the inner wall of the mould.
The constituents of the polyurethane according to the invention are mixed using a mixer. The cooling filler, the plasticizer or the fibres, when provision is made for these components or for one of these in the final composition, are also mixed with the constituents of the polyurethane using the mixer.
After the mixture has been homogenized, the propellant block is inhibited by casting the composition in the space provided in the mould or, according to a preferred procedure, by injection-moulding the composition.
The following examples, which are given merely by way of indication, illustrate the invention.
Trials of several inhibitor compositions according to the invention are carried out with the following propellant composition, expressed in percentage by weight:
______________________________________                                    
Nitrocellulose     40.2%                                                  
Nitroglycerine     36.5%                                                  
Triacetin           8.2%                                                  
Hexogen             9.1%                                                  
Additives: (combustion                                                    
                     6%                                                   
and polymerization                                                        
catalysts, ballistic                                                      
modifiers)                                                                
______________________________________
The examples of formulations of inhibitor compositions according to the invention are shown in Table 1 below:
                                  TABLE 1                                 
__________________________________________________________________________
Formulation of the compositions of the invention                          
               test no.                                                   
               1           2           3           4                      
Constituents   γ                                                    
                  %  C/O                                                  
                        R  γ                                        
                              %  C/O                                      
                                    R  γ                            
                                          %  C/O                          
                                                R  γ                
                                                      %  C/O              
                                                            R             
__________________________________________________________________________
Glycerol polyoxypropylene (1)                                             
               0,340                                                      
                  13,80    0,302                                          
                              13,80    0,344                              
                                          14,31    0,228                  
                                                      10,90               
Poly-ε-caprolactone (2)                                           
               0,056                                                      
                  12,40                                                   
                     5,3                                                  
                        1,34                                              
                           0,048                                          
                              12,00                                       
                                 5,1                                      
                                    1,29                                  
                                       0,042                              
                                           9,60                           
                                             5,2                          
                                                1                         
PHTF (6)                                           0,109                  
                                                      13,10               
                                                         5,9              
                                                            1,79          
MDCI (3)       0,605                                                      
                  16,10    0,608                                          
                              18,10    0,614                              
                                          16,20    0,634                  
                                                      20,10               
Chain extender (5)         0,044                                          
                               0,65                0,029                  
                                                      10,20               
Oxamide           52,40       50,20       54,25       49,65               
Triacetin          5,20        5,00         5,30       5,45               
Catalyst (4)       0,05        0,05        0,04       0,013               
__________________________________________________________________________
 γ: molar fraction of the constituents in the polyurethane          
 %: weight % of the constituents in the inhibitor composition             
 C/O: number of carbon atoms/number od oxygen atoms in the polyurethane   
 ##STR2##                                                                 
 (1): Polyetherpolyol marketed by the company "Ugine Kuhlman" under the   
 name "Pluracol 3130" MW = 400                                            
 (2): Lactone polymer marketed by the company "Hooker Chemical" under the 
 reference "S1036355", molecular weight (M) = 2170                        
 (3): Diisocyanate of molecular weight (M) = 262                          
 (4): Dibutyl tin dilaurate                                               
 (5): Trimethylolpropane of molecular weight (M) = 134                    
 (6): polytetrahydrofuran of molecular weight (M) = 1000 marketed by the  
 company BASF
The mechanical properties of these compositions were evaluated after aging for 15 days at 20° C. The results obtained are collated in Table 2 below.
              TABLE 2                                                     
______________________________________                                    
Mechanical properties of                                                  
the compositions of the invention                                         
composition                                                               
           Sm (bar) ε %                                           
                              E (bar)                                     
                                    e.sub.r (%)                           
______________________________________                                    
1          50       8,5       607   102                                   
2          90       8,7       1025  128                                   
3          55       9,2       598    98                                   
4          34       11,5      297   118                                   
______________________________________                                    
 Sm: maximum tensile stress at 20° C.                              
 ε: elastic elongation at 20° C.                           
 E: Young's modulus at 20° C.                                      
 e.sub.r : maximum elongation at break at 20° C.
In addition, low absorption of nitroglycerine in the inhibitor is observed.
These compositions were tested by firing cylindrical blocks (height 200 mm, φ:90 mm) of double-base propellant of the composition given above, the blocks being inhibited by a layer of these inhibitor compositions 2.5 mm in thickness.
These firings have made it possible to evaluate, on the one hand, the transverse and longitudinal transparency of the gases to radiations, to assess the discreteness of the inhibitor composition, and, on the other hand, the thermal resistance of these compositions, by the determination of the extent of ablation and the visual inspection of the combustion chamber after the firing.
The results are collated in Table 3 below.
              TABLE 3                                                     
______________________________________                                    
Results of the firing trials                                              
                 transmission                                             
          extent of    transverse                                         
                                 longitudinal                             
composition                                                               
          ablation (%) (%)       (%)                                      
______________________________________                                    
1         20-22        91         40                                      
2         16,5         90        >40                                      
3         18,5         92        >50                                      
4         18-20        >90       >40                                      
______________________________________
In addition, a total absence of any trace of melting of the composition in the combustion chamber is found after the firing, in contrast to the inhibitor compositions which do not contain lactone or tetrahydrofuran polymers.
Consequently the invention offers combustion inhibitor compositions having good discreteness properties and excellent mechanical and combustion control properties.

Claims (9)

We claim:
1. Combustion inhibitor composition for a solid propelling composition, said combustion inhibitor composition comprising an aliphatic polyurethane obtained by the reaction of at least one polyisocyanate with a mixture of at least one polyfunctional polyether polyol having a molecular weight between 400 and 4500 containing at least three hydroxy groups per molecule and at least one difunctional polymer containing two hydroxy groups per molecule, the said combustion inhibitor composition incorporating a gasifiable organic filler or an aliphatic plasticizer, wherein the said difunctional polymer is selected from the group consisting of a lactone polymer having a molecular weight between 500 and 3000 and a tetrahydrofuran polymer having a molecular weight between 600 and 2,000, the molar fractions of the difunctional polymer and of the polyfunctional polyether polyol being determined by the following relationship (I): ##EQU2## in which Mx, γx and fx, respectively, denote the molecular weight, the molar fraction and the number of OH groups per molecule of the difunctional polymer; and
My, γy and fy, respectively, denote the molecular weight, the molar fraction and the number of OH groups per molecule of the polyfunctional polyether polyol,
the proportion of the number of carbon atoms to the number of oxygen atoms in said polyurethane being greater than 4.
2. The inhibitor composition of claim 1, wherein the said difunctional polymer is a lactone polymer having a molecular weight between 1100 and 1700.
3. The inhibitor composition of claim 2, wherein the said lactone polymer is selected from the group consisting of poly-ε-caprolactone and poly-γ-butyrolactone.
4. The inhibitor composition according to claim 1, wherein the said difunctional polymer is a tetrahydrofuran polymer having a molecular weight of the order of 1000.
5. The inhibitor composition according to claim 1, wherein chain extenders selected from the group consisting of low molecular weight glycols and diamines are added to the mixture of said polymers.
6. Inhibitor composition according to claim 1,
wherein said composition contains trimethylolpropane.
7. Inhibitor composition according to claim 1,
wherein said composition contains heatstable organic or inorganic fibres.
8. Block of propellant incorporating at least on some parts of the faces thereof an inhibitor coating, wherein said coating consists of a layer of the combustion inhibitor composition of claim 1.
9. The inhibitor composition of claim 1 wherein said polyfunctional polyether polyol has a molecular weight between 400 and 1000.
US06/735,368 1984-05-17 1985-05-17 Combustion inhibitor based on an aliphatic polyurethane elastomer for a propellant, and block coated with this inhibitor Expired - Lifetime US4638735A (en)

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FR8407657 1984-05-17
FR8407657A FR2564457B1 (en) 1984-05-17 1984-05-17 COMBUSTION INHIBITOR BASED ON ALIPHATIC POLYURETHANE ELASTOMER FOR PROPERGOL, AND BLOCK COATED WITH THIS INHIBITOR

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US4799980A (en) * 1988-01-28 1989-01-24 Reed Jr Russell Multifunctional polyalkylene oxide binders
US4809612A (en) * 1981-12-11 1989-03-07 Dynamit Nobel Aktiengesellschaft Use of radiation-crosslinked polyethylene
US4950342A (en) * 1989-09-05 1990-08-21 Olin Corporation Polycaprolactone-deterred nitrocellulose propellant compositions and method
US5031539A (en) * 1990-01-19 1991-07-16 Thiokol Corporation Radiation curable rocket motor liner for case bonded solid propellant
US5345873A (en) * 1992-08-24 1994-09-13 Morton International, Inc. Gas bag inflator containing inhibited generant
US5348596A (en) * 1989-08-25 1994-09-20 Hercules Incorporated Solid propellant with non-crystalline polyether/inert plasticizer binder
WO1995000462A1 (en) * 1993-06-22 1995-01-05 Automotive Systems Laboratory, Inc. Azide-free gas generant compositions and processes
US6026749A (en) * 1973-05-11 2000-02-22 Imperial Metal Industries (Kynoch) Limited Multiple base propellant with combustion inhibitor
US6051087A (en) * 1992-01-29 2000-04-18 Cordant Technologies Inc. Low smoke rocket motor liner compositions
US6238499B1 (en) * 1999-07-16 2001-05-29 United Technologies Corporation Solid rocket propellant
US6365244B1 (en) * 1997-11-04 2002-04-02 Honeywell International, Inc. Method for heat absorption using polyoxymethylene polymer compositions
US6632378B1 (en) 2000-03-03 2003-10-14 Alliant Techsystems Inc. Nitrate ester plasticized energetic compositions, method of making and rocket motor assemblies containing the same
US20090231373A1 (en) * 2004-11-05 2009-09-17 Fujifilm Dimatix, Inc. Charge leakage prevention for inkjet printing

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JPH0794523B2 (en) * 1987-09-02 1995-10-11 東洋ゴム工業株式会社 Method for producing polyurethane polymer having excellent properties such as high moisture permeability, low swelling property and high modulus
DE102008044706A1 (en) * 2008-08-28 2010-03-04 Emery Oleochemicals Gmbh Viscosity reducer for polyether polyols

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6026749A (en) * 1973-05-11 2000-02-22 Imperial Metal Industries (Kynoch) Limited Multiple base propellant with combustion inhibitor
US4809612A (en) * 1981-12-11 1989-03-07 Dynamit Nobel Aktiengesellschaft Use of radiation-crosslinked polyethylene
US4799980A (en) * 1988-01-28 1989-01-24 Reed Jr Russell Multifunctional polyalkylene oxide binders
US5348596A (en) * 1989-08-25 1994-09-20 Hercules Incorporated Solid propellant with non-crystalline polyether/inert plasticizer binder
US4950342A (en) * 1989-09-05 1990-08-21 Olin Corporation Polycaprolactone-deterred nitrocellulose propellant compositions and method
US5031539A (en) * 1990-01-19 1991-07-16 Thiokol Corporation Radiation curable rocket motor liner for case bonded solid propellant
US6051087A (en) * 1992-01-29 2000-04-18 Cordant Technologies Inc. Low smoke rocket motor liner compositions
US5345873A (en) * 1992-08-24 1994-09-13 Morton International, Inc. Gas bag inflator containing inhibited generant
GB2284414A (en) * 1993-06-22 1995-06-07 Automotive Systems Lab Azide-free gas generant compositions and processes
GB2284414B (en) * 1993-06-22 1997-05-28 Automotive Systems Lab Azide-free gas generant compositions and processes
US5386775A (en) * 1993-06-22 1995-02-07 Automotive Systems Laboratory, Inc. Azide-free gas generant compositions and processes
WO1995000462A1 (en) * 1993-06-22 1995-01-05 Automotive Systems Laboratory, Inc. Azide-free gas generant compositions and processes
US6365244B1 (en) * 1997-11-04 2002-04-02 Honeywell International, Inc. Method for heat absorption using polyoxymethylene polymer compositions
US6238499B1 (en) * 1999-07-16 2001-05-29 United Technologies Corporation Solid rocket propellant
US6632378B1 (en) 2000-03-03 2003-10-14 Alliant Techsystems Inc. Nitrate ester plasticized energetic compositions, method of making and rocket motor assemblies containing the same
US20090231373A1 (en) * 2004-11-05 2009-09-17 Fujifilm Dimatix, Inc. Charge leakage prevention for inkjet printing

Also Published As

Publication number Publication date
JPS6110097A (en) 1986-01-17
IT1187824B (en) 1987-12-23
JPH0717474B2 (en) 1995-03-01
IT8567458A0 (en) 1985-05-17
DE3517892C2 (en) 1995-05-24
FR2564457A1 (en) 1985-11-22
DE3517892A1 (en) 1985-11-21
FR2564457B1 (en) 1986-09-26

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